findings in a new study have shown.
Researchers tested exposures to BPA, as well as bisphenol-S (BPS) and bisphenol-F (BPF), which have been introduced in recent years as BPA alternatives and are now increasingly detectable in human and animal tissues. BPS and BPF are often found in products labeled as “BPA free.”
BPS and BPF have similar physiochemical properties to BPA, and there is concern over their effects.
But their physiological impact is not yet clear, according to Puliyur MohanKumar, DVM, PhD, of the University of Georgia Regenerative Bioscience Center, Athens. “We are exposed to BPA and related compounds on a regular basis, and the important thing is that BPA and related compounds easily cross the placental barrier,” Dr. MohanKumar said during a virtual news conference held by the Endocrine Society. The study had been slated for presentation during ENDO 2020, the society's annual meeting, which was canceled because of the COVID-19 pandemic.
Dr. MohanKumar and colleagues exposed pregnant rats to BPA, BPS, or BPF. When the offspring reached adulthood, the researchers implanted them with radiotelemetry devices to track systolic and diastolic blood pressure, which they measured every 10 minutes over a 24-hour period. This was repeated once a week for 11 weeks.
“The female offspring had elevated systolic as well as diastolic blood pressure, and this was an increase of about 8 mm [Hg] higher than the control animals. That was pretty significant. Keeping these animals at such a prehypertensive state for such a long period of time is going to [lead to] lots of cardiovascular issues later on,” said Dr. MohanKumar.
Dr. Robert Sargis
Robert Sargis, MD, PhD, professor of endocrinology, diabetes, and metabolism at the University of Illinois at Chicago, noted that, although animal studies don’t necessarily translate to similar outcomes in humans, the results are cause for concern.
“What’s particularly interesting, is that there is whole area of essential hypertension, where people develop hypertension and we don’t really know why. We just treat it,” he said in an interview. “But thinking about biological origins [of hypertension] is potentially interesting for a couple of reasons. These bisphenol compounds are really common. Most Americans are exposed to bisphenol A, and it’s been associated with other adverse metabolic effects, including alterations to body weight and glucose homeostasis.
“[These findings] feed into a whole series of studies that have begun to look at the BPA replacements and the fact that they may be, at best, as bad as BPA, and at worst, possibly slightly worse, depending on which outcomes you’re looking at,” Dr. Sargis added.
In the study, seven pregnant rats were orally exposed to saline, four pregnant rats to 5 mcg/kg BPA, four to 5 mcg/kg BPS, and five to 1 mcg/kg BPF during days 6-21 of pregnancy. The lower dose of BPF was used because a dose of 5 mcg/kg proved too toxic. When the offspring reached adulthood, the researchers implanted radiotelemetry devices in the offspring’s femoral artery.
Mean daytime systolic BP was highest in the BPA group (133.3 mg Hg; P < .05), followed by BPS (132.5 mm Hg; P < .05) and BPF (129.2 mm Hg; nonsignificant), compared with 125.2 mm Hg in controls. Nighttime systolic BP was again highest in the BPA group (134.2 mm Hg; P < .01), followed by BPS (133.2 mm Hg; P < .05) and BPF (129.6 mm Hg; nonsignificant), compared with 125.1 mm Hg in controls.
During the day, diastolic BP was highest in the BPS group (91.3 mm Hg; P < .01), followed by BPA (88.8 mm Hg; nonsignificant) and BPF (88.6 mm Hg; nonsignificant), compared with 84.1 mm Hg in controls. At night, diastolic BP was highest in the BPS group (89.7 mm Hg; P < .01), followed by BPA (89.6 mm Hg; P < .01) and BPF (88.6 mm Hg; P < .01), compared with 83.3 mm Hg in controls.
During the day, mean arterial pressure was highest in the BPA group (110.5 mm Hg; P < .01), followed by BPS (108.9 mm Hg; P < .01) and BPF (105.2 mm Hg; nonsignificant), compared with 102.6 mm Hg in controls. At night, mean arterial pressure was highest in BPS (108.6 mm Hg; P < .05), followed by BPA (107.5 mm Hg; nonsignificant) and BPF (105.7 mm Hg; nonsignificant), compared with 101.8 mm Hg in controls.
“These results indicate that prenatal exposure to low levels of BPA analogs has a profound effect on hypertension” in the offspring of pregnant rats exposed to bisphenols, Dr. MohanKumar and colleagues wrote in the abstract.
He noted during his presentation that he and his colleagues plan to repeat the study in male offspring to determine if there are sex differences.
Dr. MohanKumar and colleagues reported having no relevant financial disclosures. Dr. Sargis also reported no conflicts of interest.
The research will be published in a special supplemental issue of the Journal of the Endocrine Society. In addition to a series of news conferences on March 30-31, the society will host ENDO Online 2020 during June 8-22, which will present programming for clinicians and researchers.
SOURCE: MohanKumar P et al. ENDO 2020, Abstract 719.
This article was updated on 4/17/2020.